The present invention relates generally to electronic interface devices, and more specifically to bus-powered serial cables.
The present invention provides versatility and convenience for people who use interface devices to interconnect electronic devices such as computers and peripheral devices. Interface devices, such as cables, commonly connect peripherals and computers so that functions such as data file transfer and software application loading can be performed. Examples of these peripheral devices include portable data assistants and audio file players. In some cases, such interface devices can also deliver power from the computer to the peripheral device. These peripheral devices use the delivered power to operate or to charge internal batteries. Examples of cables that transfer both data and power are bus powered serial cables such as universal serial bus (USB) and FireWire(copyright) type cables.
These bus-powered serial cables provide capabilities for high data transfer rates. Additionally, the bus-powering capabilities allow peripheral devices to have more simple designs. Even though these cables provide these benefits, improvements upon these cables can further improve a user""s experience with the cable and provide additional features. Currently, there is no manner of selectively transferring data but not power through such cables when they connect two computing devices. The ability to selectively transfer power through the cable would be very useful, for example, when a peripheral device is connected to a laptop computer that may have a limited amount of battery power to transfer. This would also be useful in cases where, for example, a peripheral device operates in certain modes depending upon whether they receive power through the bus-powered cable. Typically, to control the delivery of power to the peripheral, a user must plug or unplug the cable to use the peripheral in a desired mode. Repeated plugging and unplugging of the cable is not only tedious, but it can also cause wear and tear upon the connecting elements of the cable and the connected computing devices. Also, considering that a computer to which a peripheral is connected may have a limited amount of power, it would also be beneficial for bus-powered cables to have the capability to supply power to the peripheral device from an alternative power source.
As can be seen, even though bus-powered serial cables are very useful, improvements to these cables with respect to power transfer can increase the flexibility in how they are used.
The present invention is directed a switchable cable that can interconnect two computing devices and at least one alternative power source. A switch on the serial cable controls the delivery of power to one of the computing devices. For instance, in various switched modes, power can be drawn from the other computing device or from the alternative power source. Or, when the switch is in the xe2x80x9coffxe2x80x9d mode, no power is delivered to the computing device. The present invention provides the capability to use an alternative power source and provides a simple mechanism for selectively utilizing the alternative power source.
One aspect of the invention pertains to a cable for transmitting data and power. This cable includes a transmission medium, which transmits data signals and power, a first and a second connector formed at each end of the transmission medium, an alternative power connector, and a switch positioned on the transmission medium. The switch switches between at least two modes wherein in a first mode power is transmitted through the transmission medium between the first connector and the second connector, and wherein in a second mode power is transmitted through the transmission medium between the alternative power connector and the second connector.